After a year of gifts, roses and talk of marriage and children, Natalia Sinatora's world fell apart.

There on the television news was the man she loved, wearing shackles and handcuffs, accused of paying a hit man to kill his pregnant wife.

"I think I just sat there for about five minutes – and then the tears started coming and I couldn't stop crying," said the 24-year-old first-grade teacher, who said she had no idea her boyfriend was married. "I didn't understand. I felt sick to my stomach, and I started throwing up. It was so surreal, and probably one of the worst moments of my life."

Instead, police said, Mr. Thompson waited inside the couple's home in Allen, warned her that her husband wanted her dead and told her to call the police.

Mr. Thompson, who lives in Dallas, has not been charged with a crime. Mr. Sterling has been indicted on two counts of criminal solicitation of capital murder, one for his wife and the other for the then-unborn child. He is free on $600,000 bail with instructions not to leave Dallas and Collin counties. A pre-trial hearing is scheduled for April 13. No trial date has been set.

Mrs. Johnson-Sterling has moved in with her parents in Morgan City, La., where she gave birth to the child. She couldn't be reached for comment.

Mr. Sterling's attorney, Russell Wilson, said his client wasn't in any relationship that would motivate him to harm his wife, but of Ms. Sinatora, he said, "I acknowledge there was a relationship."

He said he would have to address Ms. Sinatora's description of the relationship in court.

"I'm not saying she has it right or wrong," he said.

For three days after the news broke on Nov. 27, Ms. Sinatora's cellphone rang nonstop. For two weeks, she said, she vomited everything she ate. She lost 15 pounds. She couldn't walk out of her bedroom without bawling or falling to the floor, she said.

She calls herself a victim – an unwitting mistress in a sordid story of murder for hire. Through Mr. Sterling's habitual lies about his family and his whereabouts, to his timely reassurances that quelled her suspicions, to guilt he made her feel about her mistrust of men borne of an unfaithful ex, Ms. Sinatora became the other woman.

During a year of elaborate deceit masked by charm, Ms. Sinatora said, Mr. Sterling told her that his wife was his ex-fiancée, and his young son, Ryan, a godchild. The only thing she's guilty of, Ms. Sinatora said, is ignoring her intuition, which whispered over and over that something was wrong.

"I swear to God, I had no idea he was married. And if I knew, I'd have gotten out," the Dallas resident said. "Then, I would have told her [Mrs. Sterling-Johnson], one woman to another. I'd want someone to do the same for me."

The other woman

Ms. Sinatora said she and Mr. Sterling met almost two years ago at the 24-Hour Fitness health club at Mockingbird Lane and Greenville Avenue in Dallas. They dated for a year, she said.

He was a popular and flirtatious fitness instructor, proud of a waiting list of students raring to take his 5:45 a.m. boxing class. She was a student of Mr. Sterling's and remains a salsa-dancing teacher at the club.

Ms. Sinatora also works as a first-grade teacher at a Dallas Independent School District elementary school. She said she's been to Mr. Sterling's workplace, a Richardson office for AT&T, which has suspended him without pay. He told Ms. Sinatora he was a project manager executing software upgrades.

"He said he worked late nights, so that's why sometimes he'd show up at my apartment at 6 a.m., 4 a.m. He'd act like he'd always get pages, and would have to go to work in the middle of the day," she said. "He acted like he worked a lot."

Mr. Sterling sometimes spent four nights a week at Ms. Sinatora's apartment, she said. He showed her pages he claimed summoned him to work.

"We'd be sitting watching TV, and he'd get up and go. He'd call me and talk to me the whole way there," she said. "He'd call me from the landline at his job. I'd call his desk. Did he have it wired to his house? I don't know. A lot of it still doesn't make sense."

Early on, Ms. Sinatora said, she heard from someone at the health club that Mr. Sterling was married. Since Mr. Sterling had given her his home phone number, she called it – and Mrs. Johnson-Sterling answered.

"I said, 'Is this Roxane Sterling? She said, 'Yes.' I said, "Hi, my name is Natalia, and I just wanted to let you know your husband is being unfaithful.' And she said, 'OK, thank you, buh-bye' and hung up."

Ms. Sinatora said she went – five times – to Mr. Sterling's house in Allen. He told her an aunt and a cousin with two young children also lived there. The unfamiliar cream Lexus was his "nice going-out car." The woman's clothes in the closet, he told her, belonged to his aunt Linda. The Roxane Sterling computer login? "I just haven't changed it."

"Of course I felt weird about it. But then he moved on to how wonderful I was and how much he loved me and how I was this amazing person ... and I just forgot about everything."

In time, Ms. Sinatora said, she wants to speak with Mrs. Johnson-Sterling.

"I want to apologize. I know I didn't do anything wrong, but I want to say, 'I'm sorry this happened to you – and I'm sorry I had to be involved,' " Ms. Sinatora said. "I want to tell her, 'I'm so sorry you're going through this, and I thank God you're alive."

Blaming herself

For a long time, Ms. Sinatora said, she blamed herself for the ordeal, thinking Mr. Sterling was going to have his wife killed to be with her. Perhaps she unknowingly provided a motive, she thought. Then, Ms. Sinatora realized she could have been in Mrs. Johnson-Sterling's shoes.

"I would have been easier to get rid of. I wasn't pregnant. I wasn't tied to him legally," she said.

When she learned Mrs. Johnson-Sterling had written a letter to urge the reduction of Mr. Sterling's bail from $1 million, Ms. Sinatora was somewhat mad, she said.

Ms. Sinatora said she would never support him.

"He's not a good man," Ms. Sinatora said. "How could anyone support someone who's had an affair? But of course, the way he manipulated me, he was probably doing the same to her."

Ms. Sinatora said she doesn't know whether Mr. Sterling dated other women during that year, though she finds it difficult to believe he had the time. Before her, maybe.

She believes he's capable of almost anything – and that includes paying someone to commit murder.

"I'm 80 percent sure [he's guilty] because of the pieces I put together in my head and all the evidence against him right now," she said. "I can't be 100 percent sure about anything until [he's] proven guilty, and that's the judicial system's job."

Asked how she couldn't have known her boyfriend was married, Ms. Sinatora said she could bring forward 25 people, plus letters and e-mails explaining Mrs. Sterling-Johnson as the ex-fiancée and Ryan as the godson.

"A lot of things don't make sense. A lot of things happened with my intuition, but he covered them up so well," she said.

Speaking out

Ms. Sinatora said she granted an interview, despite her fear of Mr. Sterling, because she worries she'll be portrayed unfairly at his upcoming trial. She said she also wants to reach out to other women who may dismiss gut instincts about the men in their lives.

She's grown tired of hearing Mr. Sterling referred to in news reports as a devoted Christian father and husband, Ms. Sinatora said.